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how does this circuit produce four sounds ? Answered

hi everyone

my friend is interested in doing this circuit but he need to understand how it's working

this is the circuit diagram 

 http://www.circuiteasy.com/animation/four%20tone%20siren%20circuit.gif

is it need 3 switches ?
and what the benefit of the transistor here ?


waiting for your help ^^

3 Replies

user
steveastrouk (author)2012-05-11

The key is the chip, where all the magic happens. The sounds are selected by the position of the switches. The transistor is a very basic amplifier.

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user
Re-design (author)2012-05-11

It uses 4 different states to get the four sounds. You can do this with 2 Spdt switches. I'd use switches with the center off. The transistor is most probably an amp.

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